The use of fluidized bed combustors to thermally oxidize various types of municipal and industrial wastes are known. For example, U.S. Pat. No. 4,196,676 to Brown et al. discloses using a fluidized bed for burning log yard waste and U.S. Pat. No. 4,777,889 to Smith discloses using a fluidized bed combustion apparatus for burning heterogeneous solid waste material, particularly materials usually found in municipal waste.
Further, U S. Pat. No. 4,769,157 to Bassler et al. discloses a process for drying sludges using a drying gas produced by the partial oxidation of sludge dried using a fluidized bed. Exhaust gases resulting from the disclosed drying process are used to produce combustible materials necessary to maintain the temperature of the bed. The present invention preferably uses a fluidized bed to dry wet sludge and the dried sludge is combined with wet sludge to give a mixture which supports autogenous combustion in a primary combustion system. The sludge is preferably sprayed onto the top of a fluidized bed under conditions selected to allow recovery of solid transportable dried combustibles which are directed to the primary combustion system for thermal oxidation.